Structure of the
Sun & Earth
Chapter 17.2, 17.3
Review from Last Time
• What are the parts of a solar
system?
– Sun (star)
– Bodies (planets, moons)
orbiting around the sun
• What is the difference between
rotation and revolution?
– Earth rotates on its axis
– Planets revolve around the
Sun on orbits
Why is the Earth Round?
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The bigger an object gets, the
more mass it has, the stronger
gravity acts on it.
When Earth was small, it was
probably a lumpy rock.
As more and more
planetesimals collided into it,
and it became more massive,
the pressure becomes huge.
So big in fact, that the rocks in
the center become crushed and
all bumps are “smoothed” over.
1. The Making of a Planet
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Earth’s layers
Have you ever tried mixing oil and
vinegar? The heavier liquid sinks
to the bottom and the lighter
material moves to the top.
It was the same with Earth.
As its rocks melted, the heavy
elements like nickel and iron sank
to the core.
Lighter materials moved to
the surface.
2. Layers of the Earth
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Earth’s First atmosphere
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Formed from the release of
gases brought to Earth by
meteorites and comets.
The atmosphere was
probably a steamy
atmosphere made of water
vapor and carbon dioxide.
The surface was very hot,
probably even molten (lava
or liquid rock) in places.
Awful science humor
• Have you heard about
the new restaurant
on the moon?
• Great food, but a
lousy atmosphere
Earth’s Second atmosphere
Earth’s second atmosphere
arose from impacts by
comets and volcanoes.
The composition was mainly
water and carbon dioxide.
The carbon dioxide kept the
planet very warm, much
warmer than it is today.
Earth’s Current atmosphere
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At some point, life began appearing.
Scientists think the first form of life was
a primitive type of bacteria that lived on
the ocean form.
Oxygen didn’t build up in the
atmosphere for a long time...though
scientists argue about why.
As plants began to cover the land,
oxygen levels increased from
photosynthesis.
Overall, it was the emergence of life
that completely changed our
atmosphere into the one we have
today.
Oceans & Continents
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After millions of years of
rainfall, water began to cover
the Earth and oceans formed.
It took much longer for the
continents to form.
As the rocks in the Earth
shifted (light materials rose
and heavy materials sank to
the core), the rock began to
float and build up along the
Earth’s surface.
Voila! You have continents!
Weird Science Tidbit
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Earth is growing heavier by
several thousand metric tons
per year!
Microscope dust constantly
filters through the
atmosphere from space and
lands on our planet.
•
Brainpop
NoW… let’s talk
about the sun!
3. Bill Nye: The Sun part 1
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Structure of the sun
Structure of the sun
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The Corona
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The outer atmosphere is called the corona.
Corona is the Latin word for crown.
See, this layer looks like a golden crown.
This layer is so thin that you can only see it during
a total solar eclipse.
• A solar eclipse is when the moon lines up directly
between the Earth & the sun and blocks the sun
from view.
4. Total Solar Eclipse
• A total eclipse as seen from Turkey, March 28, 2006.
2006 Turkey Total Solar Eclipse
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Chew on this
• What makes the sun hot?
• What makes it shine?
• How is it possible that the sun could
shine for 4.5 billion years?
• These are questions scientists have been
thinking about for years.
energy production in the sun
• Nuclear fusion, a process where two or more
nuclei join together to form a large nucleus, is
the energy that powers the sun.
• This occurs in the core of the sun.
• The temperature in the core is over 15 million
ºC and the pressure is 340 billion times the air
pressure on Earth.
• It takes millions of years for the energy to
travel from the core to the sun’s surface.
5. Bill Nye: The Sun part b
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Activity on the Surface
• The sun is basically a big ball of
boiling and churning gas.
• As a result, it is constantly
changing, both inside & out.
• The photosphere, the visible
surface of the sun, is the part that
is changing.
• Circulation of the gases within the
sun cause magnetic fields to
reach out into space.
Never look directly at the sun
• How can we see what’s
on the surface of the sun
if we can’t look directly at
it?
• There are multiple
techniques scientists
use.
• One safe method is using
a telescope to project its
image onto a white
surface.
Activity on the Surface
• Sunspots are cooler, dark spots on
the sun’s surface.
• They are related to changes in the
magnetic properties of the sun.
Activity on the Surface
• Solar flares are giant
storms on the sun’s
surface.
• They have temperatures
up to 5 million degrees
Celsius.
• The flares send out huge
streams of particles from
the sun.
Hot topics (hot... Get it?)
• The sun is a gaseous sphere made mostly of
hydrogen and helium.
• The sun has 6 layers: core, radiative zone,
convective zone, photosphere, chromosphere,
and corona.
• The sun produces energy in its core by a
process called nuclear fusion.
• Magnetic changes within the sun cause
sunspots and solar flares.
• Brainpop
6. And now… the Sun song!
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WAY HOT SOLAR FLARE VIDEOS!
• Be sure to check Mrs G’s
On Line Video Library
for some great Solar Flare Videos!